By attaching a lens structure to an imaging element such as a CCD or CMOS image sensor to which a semiconductor microfabrication technology is applied, the imaging element is mounted as a camera module on an electronic apparatus such as a digital camera or a cellular phone. An image sensor package has been proposed which includes an image sensor chip (semiconductor element) mounted on a glass substrate in order to reduce the size and weight of the camera module.
For example, in Patent Document 1, a front-illuminated CMOS image sensor package is proposed in which metal bumps for performing electrical input/output (I/O) are formed on an outer edge of a light-receiving unit located on a sensor chip surface (light-receiving surface side), and a singulated sensor chip is flip-chip mounted so that a light-receiving surface thereof faces a glass substrate.
In addition, Patent Document 2 discloses a chip size package (CSP) of a front-illuminated CMOS image sensor. Regarding the image sensor CSP, first, a glass substrate wafer and a semiconductor substrate wafer on which a sensor is formed are subjected to wafer-to-wafer bonding via an adhesive layer so as to sandwich a sensor light-receiving unit. Then, after thinning and wiring formation, singulation is performed, and thereby the image sensor CSP is completed.